Sveifluspennur í sjónhimnu : áhrif GABA-agonista

We have recorded the electroretinogram from 19 superfused eyecups of the Xeiiopus retina in order to assess the effects of agonists of the inhibitory neurotransmitter gamma-aminobutyric acid (GA¬BA), on both oscillatory potentials and the b-wave. We found that in seven eyecups the GABA uptake blocker nipecotic acid (0.1-5 mM) reduced the amplitudes of the oscillatory potentials, without having an effect on the b-wave unless it was applied in larger doses. The GABAB agonist baclofen (0.05-3 mM) reduced the amplitude of the ERG b-wave selectively in seven eyecups tested, without any effect on the amplitude of the oscillatory potentials. The GABAA agonist aminovaleric acid (0.05-3 mM) on the other hand, selectively reduced the oscillatory potentials in five, but had no reliable effects on the Xenopus b-wave. These results suggest that GABAergic mechanisms related to both A and B receptor types induce different influence on the amplitude of the oscillatory potentials and the b-wave.
Við höfum skráð sjónhimnurit úr 19 yfirflæddum augnbikurum vatnakörtu (Xenopus laevis) til þess að rannsaka áhrif mismunandi GABA- (gamma-aminobutyric acid) agonista á sveifluspennur og b-bylgju. GABA-upptökuhamlarinn NIP (nipecotic acid) (0,1-5 mM) dregur úr sveifluspennum, en hefur litil áhrif á b-bylgjuna nema í stærri skömmtum (N=7). GABAB-agonistinn baclofen (0,05-3 mM) dró sérhæft úr spennu b-bylgjunnar án þess að hafa áhrif á sveifluspennumar (N=7). GABAA-agonistinn AVA (aminovaleric acid) (0,05-3 mM) hafði hinsvegar sérhæfð áhrif til lækkunar sveifluspenna, en engin á b-bylgjuna (N=5). Þessar niðurstöður benda til þess að frumur sem hafa A og B GABA-viðtaka hafi mismunandi áhrif á sveifluspennur og b-bylgju sjónhimnurits.